The overall objective of this project is to determine what effects the antibodies, antigens, and immune complexes in colostrum have on the subsequent immune responsiveness of the nursing neonate. Specifically, the project seeks information on what and how proteins reach the colostrum and to evaluate the molecular and cellular parameters of the immunologic tolerant state induced via this route. In the next grant year we will evaluate the possibility that antigen, in the form of soluble immune complexes, can be transferred from the mother's serum into the whey and then into the nursing neonate's circulation. In addition, the effects of these transferred immune complexes, either suppressive or stimulative, on the developing immune system will be determined. Further, the ability of the mammary gland to export antigen, immune complexes, and dimeric IgA will be carefully evaluated as a function of the stage of lactation because of our recent observations.